有没有办法涂抹干爽的本金

Question

我正在编写此代码以使其更短，以便更容易学习或阅读，并且我已经提前应用了干燥和坚实的原则，所以你能帮助我如何重构这个 ruby​​ on rails 代码包含一些 if 语句来执行此操作。因此使用这些原则变得更容易阅读和更短。

if brand.rating = high
  if price_reference < 15
    price_suggestion = (price_reference - product_database.shipping_cost * 0.75) * 1.1
    price_original = price_suggestion
  elsif price_reference < 25
    price_suggestion = (price_reference - product_database.shipping_cost * 0.775) * 1.1
    price_original = price_suggestion
  elsif price_reference < 50
    price_suggestion = (price_reference - product_database.shipping_cost * 0.8) * 1.1
    price_original = price_suggestion
  elsif price_reference < 75
    price_suggestion = (price_reference - product_database.shipping_cost * 0.825) * 1.1
    price_original = price_suggestion
  elsif price_reference < 100
    price_suggestion = (price_reference - product_database.shipping_cost * 0.85) * 1.1
    price_original = price_suggestion
  elsif price_reference < 200
    price_suggestion = (price_reference - product_database.shipping_cost * 0.875) * 1.1
    price_original = price_suggestion
  elsif price_reference < 400
    price_suggestion = (price_reference - product_database.shipping_cost * 0.9) * 1.1
    price_original = price_suggestion
  elsif price_reference < 600
    price_suggestion = (price_reference - product_database.shipping_cost * 0.925) * 1.1
    price_original = price_suggestion
  else
    price_suggestion = (price_reference - product_database.shipping_cost * 0.95) * 1.1
    price_original = price_suggestion
elsif brand.rating = low
  if price_reference < 15
    price_suggestion = (price_reference - product_database.shipping_cost * 0.75) * 0.9
    price_original = price_suggestion
  elsif price_reference < 25
    price_suggestion = (price_reference - product_database.shipping_cost * 0.775) * 0.9
    price_original = price_suggestion
  elsif price_reference < 50
    price_suggestion = (price_reference - product_database.shipping_cost * 0.8) * 0.9
    price_original = price_suggestion
  elsif price_reference < 75
    price_suggestion = (price_reference - product_database.shipping_cost * 0.825) * 0.9
    price_original = price_suggestion
  elsif price_reference < 100
    price_suggestion = (price_reference - product_database.shipping_cost * 0.85) * 0.9
    price_original = price_suggestion
  elsif price_reference < 200
    price_suggestion = (price_reference - product_database.shipping_cost * 0.875) * 0.9
    price_original = price_suggestion
  elsif price_reference < 400
    price_suggestion = (price_reference - product_database.shipping_cost * 0.9) * 0.9
    price_original = price_suggestion
  elsif price_reference < 600
    price_suggestion = (price_reference - product_database.shipping_cost * 0.925) * 0.9
    price_original = price_suggestion
  else
    price_suggestion = (price_reference - product_database.shipping_cost * 0.95) * 0.9
    price_original = price_suggestion
else
  if price_reference < 15
    price_suggestion = (price_reference - product_database.shipping_cost * 0.75) * 1
    price_original = price_suggestion
  elsif price_reference < 25
    price_suggestion = (price_reference - product_database.shipping_cost * 0.775) * 1
    price_original = price_suggestion
  elsif price_reference < 50
    price_suggestion = (price_reference - product_database.shipping_cost * 0.8) * 1
    price_original = price_suggestion
  elsif price_reference < 75
    price_suggestion = (price_reference - product_database.shipping_cost * 0.825) * 1
    price_original = price_suggestion
  elsif price_reference < 100
    price_suggestion = (price_reference - product_database.shipping_cost * 0.85) * 1
    price_original = price_suggestion
  elsif price_reference < 200
    price_suggestion = (price_reference - product_database.shipping_cost * 0.875) * 1
    price_original = price_suggestion
  elsif price_reference < 400
    price_suggestion = (price_reference - product_database.shipping_cost * 0.9) * 1
    price_original = price_suggestion
  elsif price_reference < 600
    price_suggestion = (price_reference - product_database.shipping_cost * 0.925) * 1
    price_original = price_suggestion
  else
    price_suggestion = (price_reference - product_database.shipping_cost * 0.95) * 1
    price_original = price_suggestion
end

Answer 1

可能是这样的：

def suggest_price(price_reference, shipping_cost)
  [
     [15, 0.75],
     [25, 0.775],
     [50, 0.8],
     ... etc ...
  ].each do |price_point, shipping_modifier|
    if price_reference < price_point
      return price_reference - shipping_cost * shipping_modifier
    end
  end
  return price_reference - shipping_cost * 0.95
end

def price_modifier(brand)
  if brand.rating == high
    1.1 
  elsif brand.rating == low
    0.9
  else
    1
  end
end

price_original = price_modifier(brand) * suggest_price(price_reference, product_database.shipping_cost)

我并不是说这是完美的代码，但它是您可以接近它的一种方式。您可能希望价格点和修饰符保持不变。

Answer 2

您可以应用一些 OOP。在Brand 类中，您可以使用一些.case 语句使其更具可读性...

def prices
  case self.rating
    when 'high"
      case  
        when price_reference < 15
          (price_reference - product_database.shipping_cost * 0.75) * 1.1
        when price_reference < 25
          (price_reference - product_database.shipping_cost * 0.775) * 1.1
        when price_reference < 50
          (price_reference - product_database.shipping_cost * 0.8) * 1.1 
          etc...

    when 'low'
      case 
          etc...
    else
          etc...
  end
end

嵌套的case 语句更易于阅读。此外，您正在做很多不需要的变量重新分配。请记住，Ruby 总是返回它评估的最后一条语句。因此，当您在 Brand 类的成员上调用该方法时，您可以像这样使用它：

brand = Brand.new(rating: 'high', price_reference: '25')
#let's assume product_database.shipping_cost = 5
brand.prices
 #returns the value 23.2375 which came from (25 - 5 * 0.775) * 1.1

有很多方法可以做到这一点。你可以通过创建一些哈希字典来抽象出更多的代码来包含每个公式的值，然后进行变量替换来调用它们。尝试根据对象和方法来做事。 Ruby 中的一切都是某种对象，您可以创建方法来调用那些调用其他方法并使用其他对象的对象。